Detailed metallurgical investigations of worn rails and test discs show that rolling contact fatigue (RCF) crack initiation and early propagation are strongly influenced by microstructure. Also, normally benign, ductile inclusions near and at the rail surface can weaken the microstructure when transversely strain-flattened. The effect of different rail steel grades has been shown and modelled in 2D. Early surface wear 'flaking' and RCF cannot be fully modelled in 2D, given the granular nature of the formative and final microstructures, so 3D aspects of this early crack growth are examined and 3D models of the initial and strained metallurgical structures are being developed.